A reaction in which propylene and ammonia are reacted in the presence of molecular oxygen to produce acrylonitrile is known as an “ammoxidation reaction”, and this reaction is used as an industrial production method for acrylonitrile.
In this reaction, a catalyst is utilized in order to achieve a good acrylonitrile yield. For example, many catalysts comprising Mo—Bi—Fe or Fe—Sb as essential components are industrially used. Catalysts to which not only such essential components but other elements are added in order to achieve a better acrylonitrile yield are known (for example, see Patent Documents 1 and 2).
On the other hand, attempts are also made to improve the yield of acrylonitrile by making improvements in the step of preparing a catalyst though the element components constituting the catalyst are common. Patent Document 3 discloses a method involving adjusting a slurry at pH 5 or less and heat-treating the slurry at 50-120° C., and Patent Document 4 discloses a method involving adjusting a slurry at pH 6 or more and heat-treating the slurry at 50-120° C., and the like.